But I take it most pro-life activists agree that technically you are not 0 in your age when you are born, right?
Yes, but I would say that you are 0 from a "birthday" standpoint, if the basis for that is when you finally come out, which it is.
But there is no way anyone can honestly look at a developing fetus and say that it is something other than a human baby up until the moment of birth...not even pro-death folks.